This invention relates to a pad covering an air bag for use in an air bag device mounted on an automobile or the like, the air bag being inflatable when the need arises.
A conventional pad for use in an air bag device of this type, as disclosed in Japanese Utility Model Unexamined Publication No. 51-25342 and Japanese Patent Unexamined Publication No. 63-199149, is of a two-layered construction which comprises a covering layer of a soft synthetic resin provided at the outer side of the pad, and an insert portion provided at the inner side, the insert portion being made of a more rigid synthetic resin than the synthetic resin of the covering layer.
In such a conventional pad, the insert portion serves to retain the shape of the covering layer, and the side wall of the insert portion serves as a mounting portion for attaching the pad to the body of the air bag device. The insert portion further serves to prevent the upper wall of the pad from separating completely from the peripheral side wall of the pad when that upper wall is broken along a weakened portion and is unfolded upon inflation of the air bag. Therefore, the insert portion requires a predetermined rigidity and a tensile strength so as to serve these purposes.
However, in order to allow the upper wall of the pad to be easily unfolded following breakage of the upper wall thereof, the insert portion must also have flexibility in addition to having a relative rigidity and the high tensile strength. For this reason, the range of choice with respect to the shape and material of the insert portion has been considerably narrow, so that much time and labor has been required to select a proper shape and resin material for the insert portion.